Semiconductor products are used in a variety of electronic application, such as person computers, cell phones, digital cameras, and other electronic equipments. For instance, memory devices such as random-access memories (RAM) are necessarily used in many electronic devices. The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological progress in IC manufacture has produced several generations of ICs, and each generation fabricates smaller and more complex circuits than the previous generation. Several advanced techniques have been developed to implement technique nodes with smaller feature sizes, and these techniques are employed in the manufacturing of the storage devices, for example. However, while the feature size is smaller than a certain dimension, some processes have not been entirely satisfactory in all respects.